An Alternative Definition of Market Efficiency and some Comments on its Empirical Testing

An alternative definition for market efficiency, based on econometric rather than financial arguments is suggested. It is argued that this new definition, though equivalent to the existing one, has some comparative advantages. Moreover, the conditions under which the results from the application of some commonly used methods for the empirical testing of market efficiency are meaningful are examined, and guidelines for practitioners are suggested. Further, market efficiency is examined in a time-varying risk framework.Market efficiency; Return predictability; Serial correlation in stock returns; Market efficiency in the presence of conditional heteroscedasticity

Decomposing the predictive performance of the moving average trading rule of technical analysis: the contribution of linear and non linear dependencies in stock returns

On several occasions technical analysis rules have been shown to have predictive power. The main purpose of this work is to decompose the predictive power of the moving average trading rule and isolate the portion that could be attributed to the possible exploitation of linear and non linear dependencies in stock returns. Data for the General Index of the Athens Stock Exchange are filtered using linear filters so that the resulting simulated “returns” exhibit no serial correlation. Applying moving average trading rules to both the original and the simulated indices and using a statistical testing procedure that takes into account the sensitivity of the performance of the trading rule as a function of moving average length, it is found that the predictive power of the trading rule is clearly weakened when applied to the simulated index indicating that a substantial part of the rule’s predictive power is due to the exploitation of linear dependencies in stock returns. It is also found that the contribution of linear dependencies in stock returns to the performance of the trading rule is increased for shorter moving average lengths.Market Efficiency; Technical Analysis; Moving Average Trading Rules; Athens Stock Exchange.

A Note on the Use of Moving Average Trading Rules to Test For Weak from Efficiency in Capital Markets

This work focuses on the sensitivity of the performance of the moving average (MA) trading rule of technical analysis to changes in the MA length employed. Empirical analysis of daily data from NYSE, the Vienna Stock Exchange (VSE) and the Athens Stock Exchange (ASE) reveal high variability of the performance of the MA trading rule as a function of the MA length for all these markets, a result that weakens the conclusions of previous works, regarding the validity of the hypothesis of weak form market efficiency. Further, the trading rule is found to have predictive power in ASE and VSE, but not in NYSE.Efficiency of Capital Markets; Technical Analysis Trading Rules with Moving Averages; Athens Stock Exchange; New York Stock Exchange; Vienna Stock Exchange.

Familial hypercholesterolaemia in children and adolescents from 48 countries: a cross-sectional study

Background: Approximately 450 000 children are born with familial hypercholesterolaemia worldwide every year, yet only 2·1% of adults with familial hypercholesterolaemia were diagnosed before age 18 years via current diagnostic approaches, which are derived from observations in adults. We aimed to characterise children and adolescents with heterozygous familial hypercholesterolaemia (HeFH) and understand current approaches to the identification and management of familial hypercholesterolaemia to inform future public health strategies. Methods: For this cross-sectional study, we assessed children and adolescents younger than 18 years with a clinical or genetic diagnosis of HeFH at the time of entry into the Familial Hypercholesterolaemia Studies Collaboration (FHSC) registry between Oct 1, 2015, and Jan 31, 2021. Data in the registry were collected from 55 regional or national registries in 48 countries. Diagnoses relying on self-reported history of familial hypercholesterolaemia and suspected secondary hypercholesterolaemia were excluded from the registry; people with untreated LDL cholesterol (LDL-C) of at least 13·0 mmol/L were excluded from this study. Data were assessed overall and by WHO region, World Bank country income status, age, diagnostic criteria, and index-case status. The main outcome of this study was to assess current identification and management of children and adolescents with familial hypercholesterolaemia. Findings: Of 63 093 individuals in the FHSC registry, 11 848 (18·8%) were children or adolescents younger than 18 years with HeFH and were included in this study; 5756 (50·2%) of 11 476 included individuals were female and 5720 (49·8%) were male. Sex data were missing for 372 (3·1%) of 11 848 individuals. Median age at registry entry was 9·6 years (IQR 5·8-13·2). 10 099 (89·9%) of 11 235 included individuals had a final genetically confirmed diagnosis of familial hypercholesterolaemia and 1136 (10·1%) had a clinical diagnosis. Genetically confirmed diagnosis data or clinical diagnosis data were missing for 613 (5·2%) of 11 848 individuals. Genetic diagnosis was more common in children and adolescents from high-income countries (9427 [92·4%] of 10 202) than in children and adolescents from non-high-income countries (199 [48·0%] of 415). 3414 (31·6%) of 10 804 children or adolescents were index cases. Familial-hypercholesterolaemia-related physical signs, cardiovascular risk factors, and cardiovascular disease were uncommon, but were more common in non-high-income countries. 7557 (72·4%) of 10 428 included children or adolescents were not taking lipid-lowering medication (LLM) and had a median LDL-C of 5·00 mmol/L (IQR 4·05-6·08). Compared with genetic diagnosis, the use of unadapted clinical criteria intended for use in adults and reliant on more extreme phenotypes could result in 50-75% of children and adolescents with familial hypercholesterolaemia not being identified. Interpretation: Clinical characteristics observed in adults with familial hypercholesterolaemia are uncommon in children and adolescents with familial hypercholesterolaemia, hence detection in this age group relies on measurement of LDL-C and genetic confirmation. Where genetic testing is unavailable, increased availability and use of LDL-C measurements in the first few years of life could help reduce the current gap between prevalence and detection, enabling increased use of combination LLM to reach recommended LDL-C targets early in life

Efficient capital markets: A statistical definition and comments

An alternative definition for market efficiency, based on statistical rather than financial arguments is suggested, which, though equivalent with the existing one, has some comparative advantages. Further, the implications that results from some statistical tests on return predictability may have for market efficiency are discussed.Market efficiency Return predictability Serial correlation in stock returns Market efficiency in the presence of GARCH-M models

Salts of Clopidogrel: Investigation to Ensure Clinical Equivalence: A 12-Month Randomized Clinical Trial

Background: In the present clinical trial, we compared the efficacy and safety of the generic clopidogrel besylate (CB) with the innovator clopidogrel hydrogen sulfate (CHS) salt in patients eligible to receive clopidogrel. Methods: A prospective 2-arm, multicenter, open-label, phase 4 clinical trial. Consecutive patients (n = 1864) were screened and 1800 were enrolled in the trial and randomized to CHS or CB. Primary efficacy end point was the composite of myocardial infarction, stroke, or death from vascular causes, and primary safety end point was rate of bleeding events as defined by Bleeding Academic Research Consortium criteria. Results: At 12-month follow-up, no differences were observed between CB (n = 759) and CHS (n = 798) in primary efficacy and safety end points (age, sex, history of percutaneous coronary intervention adjusted odds ratio [OR], 0.70; 95% confidence interval [CI], 0.41-1.21 and OR, 0.81; 95% CI, 0.51-1.29, respectively) between CHS and CB. Analyses of efficacy and safety in subgroups that were defined according to the qualifying diagnosis revealed that there was no difference between CHS and CB. Conclusion: The efficacy and safety of CB administered for 12 months for the secondary prevention of atherothrombotic events are similar to that of CHS

Generic Clopidogrel Besylate in the Secondary Prevention of Atherothrombotic Events: A 6-month Follow-up of a Randomised Clinical Trial

Background: The aim of the present interim analysis was to compare the clinical efficacy and safety of the generic clopidogrel besylate (CB) with the innovator clopidogrel hydrogen sulphate (CHS) salt in patient groups eligible to receive clopidogrel. Methods: A 2-arm, multicenter, open-label, phase IV clinical trial. Consecutive patients (n=1,864) were screened and 1,800 were enrolled in the trial and randomized to CHS (n=759) or CB (n=798). Primary efficacy end point was the composite of myocardial infarction, stroke or death from vascular causes. Primary safety end point was the rate of bleeding events as defined by Bleeding Academic Research Consortium (BARC) criteria. Results: At 6-months follow-up no differences were observed between CB and CHS in primary efficacy end point (OR, 0.80; 95% CI, 0.37 to 1.71; p=0.57). Rates of BARC-1,-2,-3a and -5b bleeding were similar between the two study groups whereas no bleeding events according to BARC-3b, -3c, -4 and -5a were observed in either CHS or CB group. Conclusion: The clinical efficacy and safety of the generic CB were similar to those of the innovator CHS salt, thus this generic clopidogrel formulation can be routinely used in the secondary prevention of atherothrombotic events for a period of at least 6 months. (Salts of Clopidogrel: Investigation to ENsure Clinical Equivalence, SCIENCE study Clinical Trials.gov Identifier: NCT02126982)